solve assorted issue with newer pylint versions

Includes more use of 'with', adding encodings to open statements
and a couple of issues with parameter renaming.

nominatim/db/connection.py

@@ -25,7 +25,8 @@ class _Cursor(psycopg2.extras.DictCursor):
         execution functions.
     """
 
-    def execute(self, query, args=None): # pylint: disable=W0221
+    # pylint: disable=arguments-renamed,arguments-differ
+    def execute(self, query, args=None):
         """ Query execution that logs the SQL query when debugging is enabled.
         """
         LOG.debug(self.mogrify(query, args).decode('utf-8'))

nominatim/db/utils.py

@@ -40,8 +40,8 @@ def execute_file(dsn, fname, ignore_errors=False, pre_code=None, post_code=None)
         cmd.extend(('-v', 'ON_ERROR_STOP=1'))
     if not LOG.isEnabledFor(logging.INFO):
         cmd.append('--quiet')
-    proc = subprocess.Popen(cmd, env=get_pg_env(dsn), stdin=subprocess.PIPE)
 
+    with subprocess.Popen(cmd, env=get_pg_env(dsn), stdin=subprocess.PIPE) as proc:
         try:
             if not LOG.isEnabledFor(logging.INFO):
                 proc.stdin.write('set client_min_messages to WARNING;'.encode('utf-8'))

nominatim/tools/postcodes.py

@@ -36,7 +36,7 @@ class _CountryPostcodesCollector:
 
     def __init__(self, country):
         self.country = country
-        self.collected = dict()
+        self.collected = {}
 
 
     def add(self, postcode, x, y):
@@ -140,7 +140,7 @@ class _CountryPostcodesCollector:
 
         if fname.is_file():
             LOG.info("Using external postcode file '%s'.", fname)
-            return open(fname, 'r')
+            return open(fname, 'r', encoding='utf-8')
 
         fname = project_dir / f'{self.country}_postcodes.csv.gz'
 

nominatim/tools/special_phrases/sp_csv_loader.py

@@ -39,8 +39,8 @@ class SPCsvLoader(Iterator):
         """
         phrases = set()
 
-        with open(self.csv_path) as file:
-            reader = csv.DictReader(file, delimiter=',')
+        with open(self.csv_path, encoding='utf-8') as fd:
+            reader = csv.DictReader(fd, delimiter=',')
             for row in reader:
                 phrases.add(
                     SpecialPhrase(row['phrase'], row['class'], row['type'], row['operator'])